Method and apparatus for cutting glass ribbon

Abstract

A process and apparatus for cutting a continuous glass ribbon involving the use of edge restrainers such as suction cups and clamps connected to an actuator of a robot tooling through a flexible linkage capable of reciprocal motion in the direction of the ribbon velocity. The use of the flexible linkage reduces peak pulling-force when the glass ribbon is pulled or pushed laterally to during bending and separation along a pre-formed score-line. The invention can be advantageously used in the bottom of the draw of a vertical down-draw forming process.

What is claimed is: 
     
       1. A process for making a target glass sheet, comprising the following steps:
 (A) providing a precursor glass ribbon comprising an elastic portion, the elastic portion having a thickness T 1 , a width W 1 , a first major surface S 1  having a target point TP traveling with a velocity V 1 , a second major surface S 2  opposing S 1 , S 1  comprising a first peripheral region PR 1 , a second peripheral region PR 2  and a first center region CR 1 ; S 2  comprising a third peripheral region PR 3 , a fourth peripheral region PR 4  and a second center region CR 2 , where PR 1  is in opposing relation to PR 3 , PR 2  is in opposing relation to PR 4 , and CR 1  is in opposing relation to CR 2 ; 
 (B) engaging a first pair of edge rollers FR 1  having a substantially stationery rotation axle relative to the earth with PR 1  and PR 3  at a first edge roller position; 
 (C) engaging a second pair of edge rollers FR 2  having a substantially stationery rotation axle relative to the earth with PR 2  and PR 4  at a second edge roller position; 
 (D) contacting a first edge restrainer ER 1  traveling with a velocity substantially equal to V 1  with at least one of PR 1  and PR 3  at a first edge restrainer location downstream of a line SL passing through the target point TP substantially perpendicular to V 1 ; 
 (E) contacting a second edge restrainer ER 2  traveling with a velocity substantially equal to V 1  with at least one of PR 2  and PR 4  at a second edge restrainer location downstream of the line SL; 
 (F) forming a transverse score-line along the line SL on S 1  upstream of the locations of the first edge restrainer and the second edge restrainer; and 
 (G) applying to the elastic portion a breaking force F 1  perpendicular to the elastic portion below the score-line and a supporting force F 2  above the score-line in a direction opposite to that of F 1 , the direction of F 1  being pointing from S 1  to S 2 , thereby breaking the elastic portion along the score-line to obtain the target glass sheet below the score-line; wherein during step (G), a maximal force F 3  in the same direction of V 1  other than gravity is applied to the elastic portion below the score-line, and 0≦F 3 ≦400 newton; and 
 wherein before step (G), a step (G-1) is carried out: 
 (G-1) connecting ER 1  and ER 2  with an actuator through a flexible linkage capable of reciprocal motion in a direction parallel to V 1  essentially free of resistance. 
 
     
     
       2. A process in accordance with  claim 1 , wherein V 1  is essentially parallel to the gravity vector. 
     
     
       3. A process in accordance with  claim 1 , wherein 0≦F 3 ≦300 newton. 
     
     
       4. A process in accordance with  claim 1 , wherein F 3  is applied to the glass ribbon by ER 1  and/or ER 2 . 
     
     
       5. A process in accordance  claim 1 , wherein a nosing contacts S 2  in the vicinity of the score-line during steps (F) and (G). 
     
     
       6. A process in accordance with  claim 5 , wherein the nosing is a flat nosing bar extending from PR 3  to PR 4  contacting S 2  covering the score-line during step (G). 
     
     
       7. A process in accordance with  claim 5 , wherein during step (G), the nosing contacts S 2  in the vicinity of the score-line, and the nosing is adjusted to conform to the curvature of S 2  without substantially deforming the curvature of S 2 . 
     
     
       8. A process in accordance with  claim 1 , wherein ER 1  and ER 2  are selected from suction cups, clamps and rollers. 
     
     
       9. A process in accordance with  claim 8 , wherein ER 1 , ER 2  and a nosing are fixed on a platform capable of reciprocal vertical motion. 
     
     
       10. A process in accordance with  claim 1 , wherein the precursor glass ribbon further comprises a visco-elastic zone traveling with the velocity V 2  within 10 meters above the score-line, where V 2  is parallel to V 1 . 
     
     
       11. A process in accordance with  claim 1 , wherein the ratio W 1 /T 1  of the elastic zone is at least 1000. 
     
     
       12. A process for making a target glass sheet, comprising the following steps:
 (A) providing a precursor glass ribbon comprising an elastic portion, the elastic portion having a thickness T 1 , a width W 1 , a first major surface S 1  having a target point TP traveling with a velocity V 1 , a second major surface S 2  opposing S 1 , S 1  comprising a first peripheral region PR 1 , a second peripheral region PR 2  and a first center region CR 1 ; S 2  comprising a third peripheral region PR 3 , a fourth peripheral region PR 4  and a second center region CR 2 , where PR 1  is in opposing relation to PR 3 , PR 2  is in opposing relation to PR 4 , and CR 1  is in opposing relation to CR 2 ; 
 (B) engaging a first pair of edge rollers FR 1  having a substantially stationery rotation axle relative to the earth with PR 1  and PR 3  at a first edge roller position; 
 (C) engaging a second pair of edge rollers FR 2  having a substantially stationery rotation axle relative to the earth with PR 2  and PR 4  at a second edge roller position; 
 (D) contacting a first edge restrainer ER 1  traveling with a velocity substantially equal to V 1  with at least one of PR 1  and PR 3  at a first edge restrainer location downstream of a line SL passing through the target point. TP substantially perpendicular to V 1 ; 
 (E) contacting a second edge restrainer ER 2  traveling with a velocity substantially equal to V 1  with at least one of PR 2  and PR 4  at a second edge restrainer location downstream of the line SL; 
 (F) forming a transverse score-line along the line SL on S 1  upstream of the locations of the first edge restrainer and the second edge restrainer; and 
 (G) applying to the elastic portion a breaking force F 1  perpendicular to the elastic portion below the score-line and a supporting force F 2  above the score-line in a direction opposite to that of F 1 , the direction of F 1  being pointing from S 1  to S 2 , thereby breaking the elastic portion along the score-line to obtain the target glass sheet below the score-line; wherein during step (G), a maximal force F 3  in the same direction of V 1  other than gravity is applied to the elastic portion below the score-line, and 0≦F 3 ≦400 newton; and 
 wherein: 
 step (A) further comprises the following step (A1): 
 (A1) measuring the velocity V 1  substantially continuously; and 
 in steps (D) and (E), the velocities of ER 1  and ER 2  are synchronized to V 1  substantially continuously. 
 
     
     
       13. A process in accordance with  claim 12 , wherein V 1  is essentially parallel to the gravity vector. 
     
     
       14. A process in accordance with  claim 12 , wherein 0≦F 3 ≦300 newton. 
     
     
       15. A process in accordance with  claim 12 , wherein F 3  is applied to the glass ribbon by ER 1  and/or ER 2 . 
     
     
       16. A process in accordance  claim 12 , wherein a nosing contacts S 2  in the vicinity of the score-line during steps (F) and (G). 
     
     
       17. A process in accordance with  claim 16 , wherein the nosing is a flat nosing bar extending from PR 3  to PR 4  contacting S 2  covering the score-line during step (G). 
     
     
       18. A process in accordance with  claim 16 , wherein during step (G), the nosing contacts S 2  in the vicinity of the score-line, and the nosing is adjusted to conform to the curvature of S 2  without substantially deforming the curvature of S 2 . 
     
     
       19. A process in accordance with  claim 12 , wherein ER 1  and ER 2  are selected from suction cups, clamps and rollers. 
     
     
       20. A process in accordance with  claim 19 , wherein ER 1 , ER 2  and a nosing are fixed on a platform capable of reciprocal vertical motion.